Nonanalytical Concentration Dependence of Sedimentation of Charged Silica Spheres in an Organic Solvent: Experiments and Calculations
Nonanalytical Concentration Dependence of Sedimentation of Charged Silica Spheres in an Organic Solvent: Experiments and Calculations
复制标题
带电二氧化硅球在有机溶剂中沉降的非分析浓度依赖性：实验和计算
DOI：
10.1006/jcis.1995.0006
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发表时间：
1995
影响因子：
2.7
通讯作者：
R. Klein
中科院分区：
文献类型：
--
作者：
D. Thies;A. Philipse;G. Nägele;B. Mandl;R. Klein
本文研究了荷电二氧化硅球在乙醇中的沉降与离子强度和体积分数φ的关系。实验首次表明，在很低的离子强度下，归一化沉降速度U / U 0遵循1 − p φ 1/3形式的显著φ依赖性，这导致U / U 0在很低浓度下强烈下降。这种依赖关系与沉降速度的理论计算一致。但计算的数值系数p小于实验值。实验和计算都表明，对于硬球，盐的加入使φ 1/3依赖性逐渐变为线性φ依赖性。无盐分散体的φ 1/3特性使得在“无限稀释”下测量数量非常困难。
Abstract Sedimentation of charged silica spheres in ethanol has been studied as a function of ionic strength and volume fraction φ. It is shown for the first time by experiment that at very low ionic strength the normalized sedimentation velocity U / U 0 follows a remarkable φ dependence of the form 1 − p φ 1/3 , which leads to a strong decrease in U / U 0 at very low concentrations. This dependence agrees with theoretical calculations of the sedimentation velocity. The calculated numerical coefficient p , however, is smaller than the experimental value. Both experiments and calculations show that addition of salt gradually changes the φ 1/3 dependence to the linear φ dependence characteristic for hard spheres. The φ 1/3 behavior for salt-free dispersions renders it very difficult to measure quantities at “infinite dilution.”